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2.
Microsc Microanal ; 16(6): 755-63, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20961481

RESUMO

The product and direct role of the rssC gene of Serratia marcescens is unknown. For unraveling the role of the rssC gene, atomic force microscopy has been used to identify the surfaces of intact S. marcescens wild-type CH-1 cells and rssC mutant CH-1ΔC cells. The detailed surface topographies were directly visualized, and quantitative measurements of the physical properties of the membrane structures were provided. CH-1 and CH-1ΔC cells were observed before and after treatment with lysozyme, and their topography-related parameters, e.g., a valley-to-peak distance, mean height, surface roughness, and surface root-mean-square values, were defined and compared. The data obtained suggest that the cellular surface topography of mutant CH-1ΔC becomes rougher and more precipitous than that of wild-type CH-1 cells. Moreover, it was found that, compared with native wild-type CH-1, the cellular surface topography of lysozyme-treated CH-1 was not changed profoundly. The product of the rssC gene is thus predicted to be mainly responsible for fatty-acid biosynthesis of the S. marcescens outer membrane. This study represents the first direct observation of the structural changes in membranes of bacterial mutant cells and offers a new prospect for predicting gene expression in bacterial cells.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Serratia marcescens/ultraestrutura , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Deleção de Genes , Microscopia de Força Atômica , Serratia marcescens/genética , Serratia marcescens/metabolismo
3.
Biochem Biophys Res Commun ; 371(3): 462-7, 2008 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-18445479

RESUMO

Swarming in Serratia marcescens is a specialized form of bacterial populational surface migration behavior. A precocious swarming mutant S. marcescens O6 whose rssC is interrupted by mini-Tn5 transposon was obtained. The 364 amino-acid RssC showed a high identity to members of acyltransferase family. Characterization of the rssC knock-out mutant S. marcescens PC105 showed aberrant and hypervirulent phenotypes including precocious swarming behavior, reduced cell attachment ability and increase in swimming motility, flagellin synthesis, capsular polysaccharide (CPS) production, hemolysin activity, and cytotoxicity activity. Besides a more intense pattern of O-antigen sugar unit ladder, S. marcescens PC105 also showed an altered cell surface topology. A potential FlhDC binding site was identified at the rssC promoter region. In accordance, rssC transcriptional activity was up-regulated by FlhDC(Sm). Briefly, rssC is hierarchically classified as class II members in FlhDC(Sm) regulon, and reciprocally defect in rssC results in aberrant swarming and hypervirulence in S. marcescens.


Assuntos
Aciltransferases/metabolismo , Proteínas de Bactérias/metabolismo , Serratia marcescens/fisiologia , Aciltransferases/genética , Aderência Bacteriana/genética , Proteínas de Bactérias/genética , Sequência de Bases , Sítios de Ligação , Membrana Celular/ultraestrutura , Elementos de DNA Transponíveis , Regulação Bacteriana da Expressão Gênica , Dados de Sequência Molecular , Mutagênese Insercional , Regiões Promotoras Genéticas , Serratia marcescens/genética , Serratia marcescens/ultraestrutura , Transativadores/metabolismo
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